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The economics of anti-parasite defences in animals

Titel Englisch The economics of anti-parasite defences in animals
Gesuchsteller/in Christe Philippe
Nummer 104118
Förderungsinstrument Projektförderung (Abt. I-III)
Forschungseinrichtung Département d'Ecologie et d'Evolution Faculté de Biologie et de Médecine Université de Lausanne
Hochschule Universität Lausanne - LA
Hauptdisziplin Zoologie
Beginn/Ende 01.05.2004 - 31.01.2008
Bewilligter Betrag 319'925.00
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Keywords (6)

parasitism; social insects; trade-offs; collective medication; ants; immune defence

Lay Summary (Englisch)

Lay summary
Parasites and pathogens affect the survival and reproduction of their hosts, which have evolved a diverse array of defence mechanisms to resist this stress. A fundamental hypothesis in evolutionary ecology is that there is a cost to parasite resistance, which generates trade-offs between the various mechanisms of defence (immune system and behavioural defence) and fitness related life-history traits (e.g. number and quality of offspring) or social attributes (e.g. population density, queen number). So far, very few studies have measured the costs and benefits associated with various mechanisms of defence, and the complex interactions between defence mechanisms and life-history traits remain largely unknown. In this project, we investigate the costs, benefits and trade-offs of immune and behavioural defences in a diverse range of ecological and social conditions.The project focuses on the economics of two mechanisms of defence against parasites. First, we study the costs of immune system activation in the common vole Microtus arvalis. Specifically, we have performed a series of lab and field experiment in order to:(a) Test if mounting an immune response decreases the longevity of the common vole(b) Measure the energetic cost of mounting an immune response. (c) Investigate if the social stress induced by high density has an influence on immune response.(d) Evaluate the effects of the flea Nosopsyllus fasciatus on different physiological parameters of the common voles Second we investigate the costs and benefits of a recently discovered behavioural mechanism of defence, which is the use of resin by wood ants to collectively protect themselves against micro-organisms. We also take advantage of this new experimental system to investigate if there is a trade-off between various mechanisms of defence, and to test for the effect of social structure on pathogen susceptibility. We performed a series of experiments in Formica paralugubris and Formica selysi in order to:(d) Test if wood ants self-medicate with resin. For this aim, we searched for potential pathogens, tested the effect of resin on these micro-organisms, and tested if the presence of resin affects survival in experimental colonies under controlled levels of infection. Test if there is a trade-off between the use of resin and the activation of innate immune defence (estimated by measuring the level of phenoloxydase activity).(f) Test if the level of genetic diversity affects pathogen transmission and colony susceptibility.Together, these experiments will shed light on the costs and benefits of the immune system and the behavioural mechanisms of defence used by various animal taxa (mammals and ants). They might also reveal little known connections between the cost of fighting parasites and fundamental life-history traits or social characteristics. Overall, we expect that these experiments will not only reveal some fascinating adaptations of organisms to their environment, but also uncover part of the complex interactions and constraints affecting the relationship between hosts and parasites.
Direktlink auf Lay Summary Letzte Aktualisierung: 21.02.2013

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125306 Social evolution and collective defences against parasites in ants 01.01.2010 Projektförderung (Abt. I-III)
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